Quasi-single-crystalline CoO hexagrams with abundant defects for highly efficient electrocatalytic water oxidation

Zuozhong Liang; Zhehao Huang; Haitao Yuan; Zhiyuan Yang; Chaochao Zhang; Yang Xu; Wei Zhang; Haoquan Zheng; Rui Cao

doi:10.1039/c8sc02294a

Quasi-single-crystalline CoO hexagrams with abundant defects for highly efficient electrocatalytic water oxidation

Chem Sci. 2018 Jul 20;9(34):6961-6968. doi: 10.1039/c8sc02294a. eCollection 2018 Sep 14.

Authors

Zuozhong Liang¹, Zhehao Huang², Haitao Yuan¹, Zhiyuan Yang¹, Chaochao Zhang¹, Yang Xu¹, Wei Zhang¹, Haoquan Zheng¹, Rui Cao^{1

3}

Affiliations

¹ Key Laboratory of Applied Surface and Colloid Chemistry , Ministry of Education , School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an 710119 , China . Email: zhenghaoquan@snnu.edu.cn.
² Department of Materials and Environmental Chemistry , Stockholm University , SE-10691 Stockholm , Sweden.
³ Department of Chemistry , Renmin University of China , Beijing , 100872 , China . Email: ruicao@ruc.edu.cn.

Abstract

Defects and structural long-range ordering have been recognized as two crucial characters for advanced electrocatalysts. However, these two features have rarely been achieved together. Herein, we report the preparation of single-crystalline CoO hexagrams and demonstrate their exceptional electrocatalytic properties for water oxidation. The quasi-single-crystalline CoO hexagrams, prepared at the critical phase transition point of β-Co(OH)₂/Co(OH)F hexagrams, possess both abundant oxygen vacancies as defects and structural long-range ordering. The matching between the b-axis of Co(OH)F crystals and the a-axis of β-Co(OH)₂ crystals is critical for the formation of the CoO hexagram single crystals. The quasi-single-crystalline CoO hexagrams with abundant defects are highly efficient for water oxidation by delivering a 10 mA cm^-2 current density at a low overpotential of 269 mV in a 1 M KOH aqueous solution.